With the development of wireless communication technologies, various types of wireless communication schemes and technologies are being used. The typical wireless communication technologies that have been most widely used may include a cellular system and a wireless LAN system. In the wireless communication system, a terminal generally has mobility and therefore uses power of a battery, or the like. Therefore, power saving of the terminal in the wireless communication system is very important factor.
Recently, a wireless local area network (wireless LAN) has been trying to dramatically improve a physical layer (PHY) rate (PHY rate) in order to satisfy a high traffic requirement of a user. In particular, as a part of efforts to improve the PHY rate from the latest IEEE 802.11 standard, a channel bonding technique and a multiple input, multiple output (MIMO) technology have been adopted. The IEEE 802.11n standard completed in 2009 bonds two adjacent 20 MHz channels to support up to 40 MHz bandwidth and supports the use of up to four antennas and multiple streams. In the most recently completed IEEE 802.11ac, up to eight adjacent channels may be bonded to support an ultra-wideband bandwidth of 160 MHz for higher performance. Further, the IEEE 802.11ac may transmit up to 8 multiple streams and is configured to provide a 256-quadrature amplitude modulation (QAM) modulation scheme to increase data transmission efficiency.
These transmission rate improvement schemes show dramatic performance improvement in throughput in the wireless LAN system. However, the wireless LAN terminal increases complexity of the operation and dramatically increases power consumption. In order to solve the problems, the IEEE 802.11n standard has tried to reduce unnecessary power consumption due to the use of multiple antennas by defining a spatial multiplexing power save (SMPS) operation.
However, it is difficult to obtain a sufficient power saving effect in the wireless LAN system by the method alone. Therefore, there is a need for an effective method for power saving in a wireless LAN system.